This paper will investigate the replacement of one dialectal feature characteristic of bas normand (i.e. western Norman) – the evolutions of C+l – as attested in the Atlas linguistique de la France (ALF) (Edmont and Gilliéron, 1902-9; data collected in the 1890s) and the Atlas linguistique et ethnographique de la Normandie (ALEN) (Brasseur, 1981, 1984, 1997; data collected in the 1970s). These atlases show a gradual erosion of the Normand palatalised forms (Cj and Cʎ) by standard French forms (Cl). This process is not however a simple replacement of dialectal forms by non-dialectal forms but rather shows a “wave” of changes in which an earlier sound change ʎ > j is also involved. The process seems to involve a gradual reduction of the range of Cʎ in favour of Cj and of Cj in favour of Cl, with no cases of immediate replacement of Cʎ by Cl as a generalised pattern of sound change in particular local varieties. An analysis of the geographical distribution of particular words with etymological Cl further shows that the dialect atlases show relics of the passage of Cʎ to Cj and Cj to Cl which suggest a wider geographical distribution of each form. The analysis shows that in the context of convergent dialects, claiming a replacement of dialect features by standard language features is an oversimplification of the sound changes processes involved.